Wash peaches under cold running water and pat dry.

Bring a large pot of water to a rolling boil, submerge peaches for 30 seconds, then transfer to an ice bath.

Peel cooled peaches, halve, remove pits, and chop into roughly 1-inch pieces (about 8 to 10 cups).

In a medium saucepan, combine chopped peaches, sugar, and water, stir over medium heat until sugar dissolves.

Bring mixture to a gentle simmer over medium heat, approximately 5 to 8 minutes.

Maintain a gentle simmer for 15 to 20 minutes, stirring occasionally, until peaches break down and liquid thickens.

Remove from heat and let cool for 5 minutes, then strain through a fine mesh strainer over a bowl, pressing solids to extract syrup.

Stir in lemon juice and vanilla extract, taste, and adjust sweetness or brightness as desired.

Let syrup cool to room temperature, transfer to clean glass jars, seal, and refrigerate immediately.